@SuppressWarnings("unchecked")
public class MiddleTransformerRegistry<T> {
private static final int enumProtocolLength = EnumProtocol.values().length;
private final LazyNewInstance<T>[] registry = new LazyNewInstance[enumProtocolLength * 256];
private InitCallBack<T> callback;
public void register(EnumProtocol protocol, int packetId, Class<? extends T> packetTransformer) {
registry[toKey(protocol, packetId)] = new LazyNewInstance<>(packetTransformer);
}
public void setCallBack(InitCallBack<T> callback) {
this.callback = callback;
}
public T getTransformer(EnumProtocol protocol, int packetId)
throws InstantiationException, IllegalAccessException {
LazyNewInstance<T> transformer = registry[toKey(protocol, packetId)];
if (transformer == null) {
throw new NoSuchElementException(
"No transformer found for state " + protocol + " and packet id " + packetId);
}
T object = transformer.getInstance();
if (callback != null) {
callback.onInit(object);
}
return object;
}
private static class LazyNewInstance<T> {
private final Class<? extends T> clazz;
public LazyNewInstance(Class<? extends T> clazz) {
this.clazz = clazz;
}
private T instance;
public T getInstance() throws InstantiationException, IllegalAccessException {
if (instance == null) {
instance = clazz.newInstance();
}
return instance;
}
}
static int toKey(EnumProtocol protocol, int packetId) {
return (protocol.ordinal() << 8) | packetId;
}
public static interface InitCallBack<T> {
public void onInit(T object);
}
}
static int toKey(EnumProtocol protocol, int packetId) {
return (protocol.ordinal() << 8) | packetId;
}